1. Field of the Invention
This invention relates to a display method utilizing chemical changes or physical changes of monomolecular films or monomolecular layer built-up films of clathrate complexes.
2. Description of the Prior Art
Heretofore, as display mediums comprising an organic compound display layer, there have been known, for example, display mediums using organic compounds capable of forming color by redox reactions (electrochromic materials), those using fluorescent organic compounds capable of emitting light by redox reactions, and the like.
As display mediums using electrochromic materials, there are proposed various ones, for example, those disclosed in Japanese patent application laid-open Nos. 71380/1973, 32958/1975, 63950/1975 and 136000/1975.
In these conventional mediums, viologen derivatives are used as electrochromic materials, and the derivatives are dissolved in appropriate electrolytic solutions to produce color forming display layers capable of forming color by applying voltage. These are so-called organic EC (electrochromic) display elements. The color forming patterns follow the shapes of electrodes forming organic EC elements. However, in the case of the above-mentioned organic EC elements, the electrochromic materials are dissolved in electrolytic solutions and therefore, the degree of freedom is so large that the response characteristics (time required for color forming or color erasing after applying voltage) is poor. As the result, the organic EC elements can not be high density color forming elements. In addition, colored substances precipitated on electrodes are dissolved again in a solvent (electrolytic solution) so that the memory time is short and the reversibility (color forming and color erasing process) is poor. In order to resolve such drawbacks of the conventional elements, it is necessary that the above-mentioned electrochromic materials are attached to the pattern-like electrodes constituting the display elements with a high orderliness.
Various luminous display elements using fluorescent organic compounds are proposed, for example, Japanese patent application laid-open Nos. 35587/1977 and 172891/1983. These conventional ones are all concerned with EL (electroluminescence) luminous display elements having a luminous display layer composed of an electroluminescent compound and capable of emitting light by applying voltage. In particular, the elements disclosed in Japanese patent application laid-open No. 35587/1977 are constituted of a monomolecular film or a built-up film thereof composed of a derivative of anthracene, pyrene or perylene having a hydrophilic group and a hydrophobic group at appropriate positions formed on an electrode plate and a second electrode deposited on the film. In order to produce a display element of high resolution, it is desired that the distribution of luminous molecules in the film is of high orderliness. However, when the above-mentioned derivatives of anthracene and the like are used for forming a monomolecular film or a built-up film thereof having high orderliness, there are disadvantageously required careful and complicated procedures. In addition, there are also disadvantageously required fairly complicated procedures for preparing derivatives of anthracene and the like which are molecules constituting the above-mentioned monomolecular film or built-up film thereof ("Thin Solid Film", Vol. 99, pages 71-79, 1983).